1. Technical Field
The present invention relates to an airbag which is inflated and deployed to split a tear line of a cover and thereby form a door portion.
2. Related Art
Japanese Patent Application Publication No. 2008-7034 proposes an airbag device for an occupant in a front passenger seat which is arranged in an instrument panel of an automobile. The airbag device includes a case having an opening portion on an upper side. Inside the case, a folded airbag and an inflator configured to discharge gas for inflating the airbag are housed. A cover attached to extend along the instrument panel is attached to an upper portion of the case and covers the opening portion on the upper side. In an event of automobile collision, the airbag device inflates the airbag by discharging gas from the inflator, breaks the tear line formed in the cover with pressure of inflation of the airbag, and thereby forms an inflation opening. The airbag is inflated and deployed from the inflation opening, in front of the occupant in the front passenger seat to restrain the occupant and alleviate an impact applied to the occupant.
The tear line formed in the cover generally has, for example, an H-shape in a front view of the cover. By causing the splitting to start from a center tear traversing a center portion of the cover, portions on both sides of the center tear become door portions and turn to open. Depending on a structure around the airbag, there may occur a so-called lift-up phenomenon in which the deployed airbag comes into contact with an entire surface of the cover facing the airbag and causes the entire cover to bulge. In order to prevent the lift-up phenomenon, a protruding shape protruding toward the airbag needs to be provided on the surface of the cover facing the airbag, so that pressing force generated by the deployed airbag is intensely applied to a portion around the center tear, or the thickness of the cover needs to be reduced at the tear line. In the case of providing the protruding shape in the cover, the manufacturing cost increases and a space for housing the airbag is reduced. In the case of reducing the thickness of the cover at the tear line, bending and weakening of the cover occurs due to reduction of strength at the tear line.